“I Am Not Your Negro” is among the most powerful documentaries ever made about race in America.

Much of that power is to be found in the eloquent voice of the late James Baldwin. When the author died in 1987, he had completed only 30 pages of a proposed book about his relationships with three martyred civil rights icons: Medgar Evers, Malcolm X and Martin Luther King Jr.

Haitian filmmaker Raoul Peck has taken those 30 pages and fleshed them out with archival photos and footage, vintage and contemporary music, clips of Baldwin’s many TV appearances, scenes from Hollywood movies and visually stunning original footage employed for transitional passages.

Samuel L. Jackson reads Baldwin’s words.

The results are transformative.

Early on there’s an old clip from the Dick Cavett TV show. Baldwin is asked if he has much hope for the Negro’s future in America. Not much, he replies. Then the screen fills with still photos of the recent Ferguson protests.

Despite that, he seems to have been a pessimist who could not entirely tamp down his sense of hope.

Baldwin writes (and Jackson reads) of being in France and seeing photographs of a black teenage girl, surrounded by screaming whites, as she walked to her first day of class at a formerly segregated high school in the American South.

“Everybody was paying their dues,” he recalled. “It was time I went home and paid mine.”

His years in tolerant France, though, had lulled Baldwin into a comfortable place. Back in the USA he experienced a rude awakening. Racism was everywhere, no less in the North than in the South.

This is very much a personal story. Baldwin describes a childhood in which he simply assumed that all heroes were white, and then extrapolates what that meant for an entire race of people.

Never a joiner, he saw his role as that of a witness, bringing to the world the thoughts and emotions triggered by what he had seen and heard. Happily, he had the mournful/incendiary prose to get the job done.

“There are days when you wonder what your role is in this country and your future in it…I’m terrified of the moral apathy, at the death of the heart that is happening in my country.”

By refusing to face up to racial injustice, America was becoming “a nation of moral monsters.”

And in limning his friendships with Evers, King and Malcolm, Baldwin reveals how despite their initial antagonism (Malcolm found King’s nonviolence to be contemptible), these men all slowly mutated in the same direction.

Buoyed by masterful editing and brilliant sound design, “I Am Not Your Negro” unfolds less as a history lesson than as one man’s fiercely-felt ruminations.